MIPS: Refactor 'clear_page' and 'copy_page' functions.

Remove usage of the '__attribute__((alias("...")))' hack that aliased
to integer arrays containing micro-assembled instructions. This hack
breaks when building a microMIPS kernel. It also makes the code much
easier to understand.

[ralf@linux-mips.org: Added back export of the clear_page and copy_page
symbols so certain modules will work again.  Also fixed build with
CONFIG_SIBYTE_DMA_PAGEOPS enabled.]

Signed-off-by: Steven J. Hill <sjhill@mips.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/3866/
Acked-by: David Daney <david.daney@cavium.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/mm/page-funcs.S b/arch/mips/mm/page-funcs.S
new file mode 100644
index 0000000..48a6b38
--- /dev/null
+++ b/arch/mips/mm/page-funcs.S
@@ -0,0 +1,50 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Micro-assembler generated clear_page/copy_page functions.
+ *
+ * Copyright (C) 2012  MIPS Technologies, Inc.
+ * Copyright (C) 2012  Ralf Baechle <ralf@linux-mips.org>
+ */
+#include <asm/asm.h>
+#include <asm/regdef.h>
+
+#ifdef CONFIG_SIBYTE_DMA_PAGEOPS
+#define cpu_clear_page_function_name	clear_page_cpu
+#define cpu_copy_page_function_name	copy_page_cpu
+#else
+#define cpu_clear_page_function_name	clear_page
+#define cpu_copy_page_function_name	copy_page
+#endif
+
+/*
+ * Maximum sizes:
+ *
+ * R4000 128 bytes S-cache:		0x058 bytes
+ * R4600 v1.7:				0x05c bytes
+ * R4600 v2.0:				0x060 bytes
+ * With prefetching, 16 word strides	0x120 bytes
+ */
+EXPORT(__clear_page_start)
+LEAF(cpu_clear_page_function_name)
+1:	j	1b		/* Dummy, will be replaced. */
+	.space 288
+END(cpu_clear_page_function_name)
+EXPORT(__clear_page_end)
+
+/*
+ * Maximum sizes:
+ *
+ * R4000 128 bytes S-cache:		0x11c bytes
+ * R4600 v1.7:				0x080 bytes
+ * R4600 v2.0:				0x07c bytes
+ * With prefetching, 16 word strides	0x540 bytes
+ */
+EXPORT(__copy_page_start)
+LEAF(cpu_copy_page_function_name)
+1:	j	1b		/* Dummy, will be replaced. */
+	.space 1344
+END(cpu_copy_page_function_name)
+EXPORT(__copy_page_end)